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madaz
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potassium nitrate burning realy slow
hi there I'm new and appreciate any help given. Any way i have recently been trying to make black powder and am having difficulties.
I am using a 75:15:10 mix, the potassium nitrate came from a hydro shop, the surfer is from a garden shop and the charcoal is my own all the
ingredients are supposed to be pure.
Every mix i have had no matter how fine has burnt slow and left allot of slag.
Are there any tests i can do to find out how pure the kno3 is?
thank you.
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chemkid
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sulfur from the garden shop is usually only 90% that may be a problem as well
There is a good thread on it a while back, mixing with water will purify it somewhat. Or you can distill it.
Chemkid
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madaz
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It says on the bottle that its 1000grams per kilogram sulfer. But i will try any way.
thank you
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MagicJigPipe
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I never had any problems with black powder burning too slow. I used saltpeter from a pharmacy, sublimed sulfer and ground up activated charcoal
(because I had a bunch of it).
In fact, I just used a tablespoon to measure.
And, btw, BP isn't supposed to burn extremely fast and always leaves residue. That's why muzzleloaders must be cleaned so often.
If you need some I have about 25lbs (11.3kg) that I bought from a "retired" Civil War reenactor. Can't ship it of course (or can I?) but I definitely
don't need it all.
And if you don't mind selling a kidney you can just go to Wal-Mart and buy Pyrodex which is basically FFG black powder with a few "proprietary"
ingredients.
[Edited on 2-1-2008 by MagicJigPipe]
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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Twospoons
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You are mixing by weight, and ball-milling?
My last lot of BP burned unbelievably fast (a 'thump' from a loose pile) and left only a smear of soot.
Fert. grade nitrate, garden sulphur and BBQ charcoal
[Edited on 3-1-2008 by Twospoons]
Helicopter: "helico" -> spiral, "pter" -> with wings
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madaz
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For some reason i get alot of residue eg for every tbl spoon i burn i will get half a tbl spoon of slag.
And it takes about 10 seconds to burn that tbl spoon about the same speed as thermite.
I reside is aus so unfortunately its alot harder to get otc chemicals.
Thank you for your offer but certain government bodies would not be happy for this transaction to take place not to mention freight.
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chemoleo
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Homemade blackpowder does indeed burn comparably slowly, regardless of the quality of reagents. There's a whole art to making blackpowder properly.
Commercial blackpowder used for hunting rifles burns like a flash, even if drawn out in a line 30 cm long it burns instantaneously, i.e. you cannot
follow the progression of deflagration by eye.
Regardless, this isn't really the place to discuss this in depth, certain places such as the APC forum cater for needs such as yours. You may want to
take your query there.
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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madaz
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I am mixing buy weight but I'm currently using a mortar and pestle grinding individually of coarse, upon mixing i obtain a fine light gray powder. I
am in the process of fabricating a ball mill.
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MagicJigPipe
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I have never seen black powder burn so fast I couldn't follow it. Are you sure you don't mean nitrocellulose?
Of course there are many different kinds of BP. Different mixtures, grain sizes and various other things.
I suppose commercial FFFG or finer would burn that fast. I just never used it.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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madaz
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Thank you for that forum im reading up now.
In commercial BP are there any different ingredients (I've seen a couple with sodium nitrate) or is it to do with the manufacturing process?
Also is my kno3 supposed to feel soapy?
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Twospoons
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It shouldn't be light grey. It should be black, or very dark grey. Sounds to me like you don't have enough charcoal in there - which would tally
with the residue, and the slow burn. When I make mine there is almost as much charcoal as nitrate by volume.
Ball milling makes a HUGE difference to the burn speed.
Helicopter: "helico" -> spiral, "pter" -> with wings
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madaz
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Thank you i will check my scales and finish the ball mill. Dose hardwood charcoal have a adverse effect on speed?
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Twospoons
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No idea if hardwood charcoal is that bad. Softwood is usually used - mine was pine based IIRC. It would help to grind all the ingredients together
- do it wet, with gloves and face protection. Press the damp BP through a sieve to granulate it and let it dry.
Helicopter: "helico" -> spiral, "pter" -> with wings
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madaz
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Ok i will I'm reading APC forums and they have some interesting info on charcoal.
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Mumbles
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The charcoal has easily the largest impact upon the speed of the charcoal. However, it is your method of preparation that is likely the culprit here.
I have made reasonable quality black powder from a mortar and pestle before. It sounds like you are not getting the materials intimate enough. With
increased intimacy, comes less "slag" or "pearls" which is the product you have left over. Good powder should have very little residue.
Charcoal: Each variety provides it's own traits. Think of the charcoal kind of like the DNA of black powder. It gives the specific traits to the
batch. For speed, reasonably light weight, hardwood species are typically chosen. Willows, poplar, alder, balsa, maple all will provide pretty good
results. There are dozens and dozens more, but it would take a considerable amount of time and space to go through all the charcoal stuff. Other
things like pines, cedar, and locusts tend to give slower speeds, but provide very long hanging tails. There are exceptions of course, I believe
white pine and spruce gives pretty fast BP, but that is just off the top of my head.
The sulfur isn't so important. Many wettable sulfurs contain clay or chalk. Even 90% sulfur(a common product), will still only contribute 1% of
contaminant to the final product. The same is true with the KNO3. Fertilizer grade is often a bit contaminated. I have 500lbs so I have to live
with the contaminations. If you feel it is causing your product to be decreased in quality to a significant degree, recrystalizing it from water will
yield a much purer product. The soapiness is probably some residual carbonate or hydroxide from it's manufacture. It is sometimes coated with
something to make it flow a bit better.
The scale could be an issue. Pyrotechnics is a bit more forgiving than chemistry. A percent here or there is going to be barely noticeable. Still,
I try to shoot for less than 5% systematic error in the smallest portion. For a 100g batch, 5% error would be half a gram from the sulfur
measurement. Thus a scale accurate to at least .5g would be ideal. Preferably, .1g or better resolution is even better.
One thing that may help with the mortar and pestle production is to grind it slightly damp. Add a few percent water by weight, and grind. It is said
to help incorporate the ingredients more intimatly. Wetting it, for me at least always seems to speed it up when it dries. I even ball mill my
product slightly wet.
Commercially, the 75-15-10 proportion is pretty much followed to my knowledge. Slight variations may exist. They pregrind all their chemicals to
dust in giant ball mills. They then wheel mill the product. Look at pictures of old flour mills with the giant stone wheels to get an idea. The
product using sodium nitrate is known as "blasting B" powder. It burns slower and heaves more than the potassium nitrate variety. After it is wheel
milled, it is wet more, and pressed into large pucks. It gets broken up into granules and screened to specific sizes based upon use. The pressing
provides increased bulk density, and prevents the product from being crushed in use and transport. This provides increased reliability and
repeatability.
As far as speed. Good powder will burn in an instant. It should be noted that very fine powder, sometimes called meal dust, can actually be too
fine. Think on the consistency of flour. It becomes so fine it acts more as a liquid than a solid. Granulating the product will help to create
balls of composition that will burn faster. The rough, uneven surfaces will also catch fire much easier. When I take the product out of the ball
mill it is usually caked enough to form little, but very weak granules on it's own. My test is to put a lit match on it. When my product has been
milled enough, it will burn fast enough to put the match out. Quite literally a poof in an instant. It is also capable of burning on a piece of
computer paper without scorching it.
[Edited on 1-2-2008 by Mumbles]
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madaz
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Thank you for sharing your experience this helps alot. Are you by chance the same Mumbles as on the APC forum?
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Mumbles
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Indeed I am. Given my status there, I unfortunatly do not get to visit here as much as I would like. Running a forum takes up some considerable
amount of time.
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asilentbob
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For the record Pyrodex should not be treated like black powder unless in muzzle loaders and even then its burning characteristics are significantly
different. IIRC it contains potassium perchlorate, charcoal, potassium nitrate, (I want to say sulfur and/or a benzoic acid salt), and a binder or
two. For it to burn like black powder it needs very good confinement like in a muzzle loader barrel. Trying to use it to lift a shell or as a
propellant in a rocket (ramming would be very dangerous) would likely not work very well though it has been done before. Trying to mill it to a fine
powder for general priming purposes could be disastrous perchlorate/fuel is not something you want to mill. Perchlorate/sulfur is less sensitive than
chlorate/sulfur, but it is still pretty sensitive.
So many ideas... too few dealing with chemistry.
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DerAlte
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IMO Mumbles and Twospoons have it right. Any amount of pestle and mortar fining of the materials will not make a fast BP. You must use water to
dissolve the KNO3 in order to make a truly finely interspersed microcrystalline mixture and then get it thoroughly dry. The purity of ingredients and
exact mix within a few % don't matter a damn. Hardwood charcoals do seem better but that's not essential.
The secret is in the preparation. You should get a hard cake of dried BP - one good way is to dry it slowly on a plate under a halogen lamp, but you
can do it also in an over at a low controlled temp, say 120C. Slowly, be in no hurry! Then grind it up. Such a mixture will burn very quickly and if
confined, explode.
Maybe I shouldn't be telling this...
Der Alte
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Mumbles
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Spreading the granulated product on a few sheets of news paper will have it dry pretty quickly. Stir it every so often to cycle the dry material off
the top. I don't know if I would go as far as to suggest putting it in an oven. It seems to be a tad over kill in my opinion, and bordering on the
unsafe. My experience is that movement of dry air can force dry materials faster than simply hot air can. The water evaporates quite quickly. I use
a box fan some distance away just to circulate the air around my drying area. To be fair, I've never exceeded 50C in air temperature trying to dry
anything either.
There are plans around for drying boxes that utilize a small heat source (think 60W light bulb), and a dehumidifier in an enclosed cabinet. This is
really over kill for most unless you are very seriously into pyrotechnics and require strong force drying.
Something else I should have mentioned, if going to granulate, as for a lifting charge, it is advisable to use a water based binder. There is a
product often refered to dextrin that is often used. Dextrin is a bit different from the class of compounds refered to as "dextrins" people in
brewing may be familiar with. I have heard good things about liquid laundry starch as well.
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MagicJigPipe
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In my experiences Pyrodex is actually better for "lifting" things than black powder. When I have something that has to be done correctly, that's what
I use. Most of the time I can't really tell a difference (and the difference is usually in favor of the Pyrodex).
It's just so damn expensive.
EDIT
My question is. Why not just buy some black powder? It's easier to get than any lab chemical. It's even easier to get than KNO3 in my experience.
[Edited on 3-1-2008 by MagicJigPipe]
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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madaz
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Thank you everyone for your in put.
I have no access to this Pyrodex compound and buying black powder in aus is near impossible.
Since yesterday i have found my charcoal was mainly to blame, after reading a charcoal post on APC i made some plum tree charcoal out of my back yard
and this preformed very well.
Is there a good tutorial on the water method?
thank you.
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Xenoid
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@ madaz
Forget Hodgdon Pyrodex, it's a modified, controlled burn black powder especially designed as a muzzleloading propellent. I bought some at a sports
(ammo, rifle) shop. I just wanted to see how it compared to homemade black powder. Being an American product it cost the F*%#ing earth, and it was
crap.
First grind your potassium nitrate in a coffee grinder, grind your charcoal (barbecue charcoal is fine) in a cheap blender. I've picked up cheap
blenders at recycling centres for a few dollars. You may need to sieve the charcoal, and dust goes everywhere, do it outside. Always use seperate
grinders/blenders for oxidisers/fuels!
Grind the combined, weighed ingredients dampened with water in a mortar and pestle. It's hard work, do a little at a time. That's why people use ball
mills.
Dry, and lightly powder.
Note: The addition of water is actually an important step to get fast burning powder. The grains of charcoal have an enormous surface area, due to all
the little pores, the water dissolves some of the nitrate and is absorbed into the pores. When dried, the KNO3 crystallises inside the grains of
charcoal, coating the surfaces. This is why it burns so much better.
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len1
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| Quote: | Originally posted by DerAlte
You should get a hard cake of dried BP - one good way is to dry it slowly on a plate under a halogen lamp, but you can do it also in an over at a low
controlled temp, say 120C. Slowly, be in no hurry! Then grind it up. Such a mixture will burn very quickly and if confined, explode.
Maybe I shouldn't be telling this...
Der Alte |
I have never made BP, but if the powder so made can explode when confined, how can you grind it?
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Xenoid
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| Quote: | Originally posted by len1
I have never made BP, but if the powder so made can explode when confined, how can you grind it? |
He means confined in a firework, cannon, gun, pipe etc. so that when ignited, pressure builds up. This accelerates the combustion, resulting in an
explosion. Many other true explosives, require only heat, friction or shock to make them exploded. They don't need to be confined.
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